n = int(input())
s = ['0']
for i in range(500000):
    s.append(0)
for i in range(n):
    m = list(map(float,input().split()))
    a = m[0]
    b = int(m[1])
    for j in range(1,b+1):
        a = int(a*j)
        if s[a] == 0:
            s[a] = '1'
        else:
            s[a] = '0'
        a = m[0]
c = s.index('1')
print(c)